20 MONTHLY WEATHER REVIEW. JANUARY,1901

which, from a topographical view, is a trough in the great These observations demonstrate the importance of inver- American Plateau. For 400 miles eastward from its inter- sions of temperature in the vertical, as soon as the cyclonic section with the western boundary of the &ttite, tho surface of condition has ceased to exist; a decrease of temperature, this valley ranges from 1,000 to 4,000 feet above sea level, very slight in the first 1,200 meters, is an alniost certain indi- while the mountaius that snrroutid it on the north,east, south, cation of fine weather the next day. aud west vary in height from 6,000 to 10,000 feet. Briefly, As with the Americans so with us-our ascensione have in- these are the prominent topogrnphiaal characteristics of the creased in height as our materials have improved, and we State of Idaho that bear up011our subject. have learned better how to start the kites. It is not generally known that the Siiake River Valley, The vicinity of several lines of railroad, aud of quite a covering one-third of the State, has a climate so mild in the crowded network of telegraph wires prevented us in many winter season as to be the natural home for stock from the cases from letting out long lines of kite wire, the slightest ac- first fall of heavy snow 011 the mountaius until signs of spriug cident causing our line to be carried doan to the railroad appear. In this favored valley thousands of sheep, horses, track. Nevertheless, the very first year we attained an eleva- atid cattle seek refuge from the storms and cold waves of tion of 2,000 meters, then 4,500,and 3,850 meters. Finally, winter. Not only does the mildness of the temperature ofl’er September last, we were able to raise our instriinients as high inducemeiit to the herder to establish his winter quarters as 4,300 meters. here, but the almost total ahelice of snow and the presence Whatever be the success obtained hy the kite the altitudes of growing grass enable the stock to subsist during mild reached are uecessarily limited. Moreover, they can not winters upon what nature alone has provided. ascend at all in calm weather; we must., therefore, have re- Why should the Stiake River Valley be mild when to the course to balloons i~]order to explore the atmosphere niore southward, over the plateau States, the normal condition dur- thoroughly. The ascensions of the “ AQrophiles”of Messrs. iiig the whiter season is an area of high pressure prevailing Herniite and B4saucon showed: for weeks without great floctuationY There is no explanation ( 1) That the temperature was much lower than was sup- for it unless the air when flowing over the mountains from posed from the observations made on mountains, since a the high pressure area down into the Snake River Valley is temperature of -60° was found at air altitude below 14,000 heated by compression. meters. Duriiig tlie winter season storms pass in succession over (3) That the gas inside of the balloon cooled very rapidly, the Caiiadian Northwest bringing Idaho continually within so as to approach the thenretical teiiiperature obtained by the field of influence, though the center of disturbance almost the expansion of the gas for the same differences of pres- invariably reniains in the north. It is during tlie prevalence sure. This fact, which has been neglected up to the present of the storn~sin the north that Idaho remains in the foot- time, because it is geuerally concealed hy the great rise of hills of the high pressure area prevailing over the plateau tenrperature produced when tlie balloon is exposed to the ~un, States with tho barometer (reduced to sea-level) reading is of considerahle practical importance, and must be taken 30.40 to 30.80 at Idaho Falls, Salt Lake City, Denver, and into account in calculating the height that caii be reached Carson City, and moderately high at Baker City, varying, ap- hy a balloon ascending in the night. pareirtly, with the declivity of the depression it1 the irortli. (3) These ascensions have led M. Herniite to construct a The drift of the air from the high pressure area of the Platenu form of shelter called “ parasoliel,” for shelteriilg the instru- occurs with each appearance of a depressioli over Alberta, and ments from solar radiation. This “parasoleil ” consists of as the air drifts over the network of mountains to the south a paper tube blackened on the inside, and covered on the out- and west of the Snake River Valley the principle of dynamic side with a sheet of metal in such a way as to become heated heating conies into operation. to the least possible degree under the direct action of the When the high area disappears from the Plateau, per- sun. mitting the troughs from tlie low pressure field to sweep Since the meteorological conference at Paris in 1596, an southward through the State into Utah, Nevada, and Arizona, interiiatioiial agreement has been entered into, and at cer- then the cold weather occurs in Idaho, siirccr the slightest de- tain fixed times, sounding halloons have been sent up from pression passing southward through the State is productive of Paris, Berlin, Strasburg, Vienna, Munich, and St. Petersburg. a fall in temperature and is suficiet~tto justify the issuance These ascensions, six in number, are not as yet siifficien tly of frost warnings as late in the season as July. numerous to lead to the discovery of very precise laws, hut Since the Weather Bureau established the station at Boise have enabled us to study the methods and to explain many persistent effort has been made to induce those to whom the details. daily weather niap is accessihle to comprehend these plain In view of the diversity in the atmospheric conditions and rules. Not nntil February 3, 1899, when Idaho was visited of the rapidity with which the phenomena change from day by a cold wave of unusual severity which resulted in loss of to day, I have thought it necessary to make very frequent stock, did those who were vitally interested comprehend that aerial soundings-when necessary, several times a week-and their loss would have been materially lessetied had they for this purpose we have first turned our attention to render- heeded the warnings which gave time for ample protection. ing the usage of sounding balloons niore simple and less expensive. We have attained this result by employing pure hydrogen, which allows of greatly diminishing the diameter of the bal- STUDIES ON !lXE ATMOSPHERE AT TRAPPES, FRANCE.’ loons and of diminishing the weight of the instruments sent up, without, however, impairing their accuracy. By Y. LEONTEISSERENC DE BORT. In order to send up these balloons even in violent winds or Since the autunin of 1S97 niore tlran a hundred and fifty stormy weather, which has scarcely ever been attempted, but kite ascensions have been made at the Trappes Observatory, ie of tho greatest interest, I sought a device which would although the atmospheric conditioiis are less favorable than enable us to start the balloon, when once it is inflated, without those on the Aiiierican coast. exposing it to injury from the very first gusts, since we desire ...... always to use extra light netting. For this purpose I adopted ‘Translated from the Journal de Physique, (3) Vol. IS, March, 1900, the followiug arrangement : I constructed, upon a revolving pp. 133-137. table, a very light tent, open on one side. The balloon once

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inflated in this tent, care is taken to keep the opening turned MONTHLY STATEMENT OF AVEFCAGm WBATm CON- away from the wind. The iustruments are attached to the balloon, as is also a “ballast heaver,” filled with sand or DITIONS FOR JANUARY. some liquid and provided with an aperture arranged in such By Prof. E. B. Q~ts10l.r. a mariner that it can empty itself in the proper interval, gen- erally in about forty minutes. The balloon is then brought The following statements are based on average weather con- to the door of the tent; the ballast heaver is supported so as ditions for January, as determined by long series of obser- to facilitate the rising of the balloon a little, and the whole vations. As the weather of any given January does not is then launched into the air with the least possible shake. Thanks to this device, we have been able to send up sounding conform strictly to the average conditions the statements balloons during storms in which the wind reached a velocity can not be considered as forecasts: of 14 meters per second. January is a month of severe storms in the middle latitudes To avoid the disturbing influence of the rays of the sun of the North Atlantic Ocean. Along the transatlantic stearn- and, above all, the radiation of the upper clouds when they ship tracks these storms set in with southeast gales which are in great masses and form that sea of dazzliug clouds so ehift to west and northwest with freezing temperature. West- well known to alpine travelers and aeronauts, we have made ward bound vessels experience sudden shifts of wind from the the greater number of our night ascensions at first by moon- southeast and storms of comparatively short duration, and light-with a great deal of trouble, I must confess-and after- have prevailing strong head (westerly) winds. Storms en- wards,when I succeeded in improving our apparatus, by electric countered by eastward bound vessels are fewer in uumber and light. Since the month of March, 1899, we have sent up more of longer duration ; the vessels and the storms travel in the than a hundred and twenty balloons which have broiight back same direction. Storms seldom appear in the tropical re- curves of pressure and temperature. The height of 13,000 gions of the Atlantic and Pacific oceans in January. On the meters has been attained twenty-four times ; 14,000 meters, north coast of western Cuba, however, and in the Gulf of eight times ; 15,000 meters, three times. Mexico, high and cold north winds are not uncommon during We can with our present outfit reach a height of 13,000 the winter months. meters nearly every time. In the Lake region and the Atlantic coast districts of the Confining the discussion of the observations collected to United States the severest January storms come from the the atmosphere up to a height of 10,OOO meters, the region middle-West and Southwest, with northeast shifting to north- explored by the greater number of the balloons, we see : weet gales; snow occurs on the north and rain or light snow 1. That the differences of temperature from one day to on the south of the paths of the storms. In the Pacific coast another may be greater at 7,000 or 8,000 meters than those States the rainy season is at its height, and strong gales occur observed the same day near the gronnd. This fact is of con- from the central California coast to Alaska; In the Plateau siderable importance and is .besides contrary to the ideas we and Rocky Mountaiu districts and on the great Plains the had previously formed on the subject. prevailing weather is fine and cold. This entire region is, 2. We see that the temperaturediminishes much faster near however, subject to occasional cold waves of great severity, the centers of depression than elsewhere. This diminution which, with snow and high wiuds, sweep southward to K’ew reaches in certain cases about 0.90° C. per 100 meters. Mexico aiid Texas and sometimes to the Rio Grande and north- Finally, it is remarked that in a great many areas of high ern Mexico, causiug great losses of stock 011 the great ranges. pressure-I do not say in all-the decrease of temperature Frost is likely to occur in any part of the United States takes place in the following manner: from the ground to in January, and about. once in five years severe freezes occur 1,600 or 2,000 meters the temperature varies little and some- in the Gulf coast districts and in central and northern times even increases, after which it begins to diminish in a Florida. normal manner, and finishes by reaching at 9,OOO or 10,OOO meters a decrease of lo per 100 meters. If we compare these values with those observed in the low areas we see that the CLIMATOLOaY OF UOSTA RIUA. variation in the vertical shows ordinarily the following characteristics : Cornmunlcated by E. PIWIER,Director, Physical Qeographic Institute. The lower strata are often warmer iu the areas of low pres- sure than in the areas of high pressure ; but above several In conimunicating this abstract of the meteorological ob- hundred meters of altitude the rapid dimiuution of tempera- servations made in Costa Rica during January, 1901, and ture produces lower temperatures iu the low areas. under date of February 20, Mr. Pittier says : Thus, the center of a depressiou at about 3,000 or 4,000 meters altitude is ordinarily colder than the corresponding part of the barqmetric maximum. This fact had already been demonstrated by Hanu in his mountain observations ; but the sounding balloons, while confirming this first result, show that higher up the temperatures have again a tendency to equalize themselves, and this is of great importance relative to the form of the upper isobars. I would like to be able to say a few words about the tem- perature of the highest atmosphere, that which extends above the ordinary region of the cirrus clouds; but notwithstand- ing that we have observations at these altitudes, we shall have to wait to diecuss them until we are certain that the thr- mometer-when the air is so greatly rarefied-is able, by simple contact, to come into thermal equilibrium with its surroundings. If it cannot, then we shall have to make use of special methods for determining the temperature at high a1ti tudes.

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